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Body fluids suspected of bacterial infection were cultured and examined for the presence of D-lactic acid, a specific bacterial metabolite. We examined 206 patients and 264 specimens. D-Lactic acid was found in concentrations of greater than or equal to 0.15 mM in 11 of 11 infected and 6 of 40 noninfected ascitic fluids, 6 of 6 infected and 4 of 33 noninfected pleural fluids, 4 of 4 infected and 0 of 13 noninfected synovial fluids, and 26 of 27 infected and 2 of 130 noninfected cerebrospinal fluids. The overall sensitivity was 79.7%, and the specificity was 99.5% when the D-lactic acid concentration was at least 0.15 mM. The most important clinical utility of the D-lactic acid measurement appears to be for patients with bacterial infection in various body compartments and in patients who have already received antimicrobial therapy. An elevation in D-lactic acid may indicate the presence of bacterial infection even when cultures are negative.

Several commercial systems are available to distinguish between Staphylococcus aureus and the coagulase-negative species of the Micrococcaceae family. Four latex agglutination systems (Accu-Staph, SeroSTAT, Staphaurex, and Staphylatex) and two hemagglutination systems (Hemastaph and Staphyloslide) were compared for their performance in the rapid identification of 232 isolates of staphylococci, including 114 of methicillin-resistant S. aureus. Accu-Staph, Staphaurex, and Staphyloslide correctly identified 100% of the methicillin-resistant S. aureus isolates; Hemastaph and Staphylatex, 99.1%; and SeroSTAT, 94.7%. Most reactions were easy to interpret, although 15% of the SeroSTAT reactions were weak. Autoagglutination occurred only with isolates of coagulase-negative staphylococci. False-positive reactions were rare and occurred only with systems which did not detect autoagglutination. Five of these six systems appear to be adequate for the rapid identification of S. aureus, including methicillin-resistant isolates.

The BACTEC resin-containing blood culture bottle (16B; Johnston Laboratories) was designed to bind antibiotics and to support bacterial growth. However, only modest increases in the recovery rates of pathogens have been found in clinical studies. This in vitro study evaluated the ability of the 16B to recover organisms from human serum containing clinically achievable concentrations of antibiotics. Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Haemophilus influenzae, Staphylococcus aureus, Streptococcus faecalis, and a viridans streptococcus were added to serum containing antibiotic(s), and at various time intervals of antibiotic exposure, portions were removed and inoculated into both the 16B and the 6B (conventional aerobic) bottles. The studies of the kinetics of killing of the bacterial strains by the various antibiotics showed a good correlation between those combinations of bacteria-antibiotic(s) which produced slow killing and the combinations of bacteria-antibiotic(s) which were recovered preferentially in the 16B bottles. Low recovery rates were noted when the antibiotics killed the organisms rapidly. The indications for use of the resin-containing blood culture bottle should be limited to those situations in which the patient is receiving antibiotics and the bacteremia is suspected to involve a pathogen which is killed slowly by the administered drug(s) or when the bacteremia is continuous. The failure of the BACTEC 16B blood culture bottle to recover organisms may in part reflect the bactericidal activity of the antibiotics administered.

Because of the emergence of drug-resistant Klebsiella strains in many hospitals, the distribution of the serotypes was reexamined to determine whether there was any correlation between the serotype and the site of isolation from the body, the antimicrobial susceptibility pattern, or the place of acquisition of the organism (hospital or community). One hundred consecutive isolates of Klebsiella pneumoniae from different patients were typed as 1, 2, 3, 4, 5, 6, or greater than 6. Of these, 8 of 28 strains isolated from respiratory secretions were serotype 2 (9 typable strains), 6 of 24 wound isolates were serotype 3 (8 typable strains), and the urine isolates varied in their serotypes. Regardless of serotype, most strains appeared mucoid on blood and MacConkey agars. Twenty-six percent of the isolates were resistant to at least one antimicrobial agent. No correlation was found between the serotypes and the antibiotic resistance; however, strains isolated within 25 days of admission to the hospital from the community were all susceptible. It appears that although there may be a correlation between the serotype and isolation from some sites of the body, knowledge of the serotype of the organism cannot predict the antimicrobial susceptibility pattern. The clinician's choice of antibiotic therapy should depend largely on whether the Klebsiella strain was acquired by the patient in the community (0% resistant) or in the hospital (31% resistant).

With the Enterobacteriaceae Plus Biochemical Card, the AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.) is purported to identify members of the family Enterobacteriaceae and seven species of glucose-nonfermenting gram-negative rods: Pseudomonas aeruginosa, P. fluorescens, P. putida, P. maltophilia, P. cepacia, and Acinetobacter calcoaceticus (saccharolytic and non-saccharolytic). The latter capability was examined in this investigation. Of 410 glucose-nonfermenting rods included in the identification profile, the AutoMicrobic system correctly identified 366 (89.3%). Of 62 glucose-nonfermenting organisms not included in the identification profile, 41 (66%) were correctly reported as "unidentified organism." The usefulness of the AutoMicrobic system-generated identification probability in establishing criteria for acceptance of identification is discussed.

Reported here is the case of a patient with metastatic adenocarcinoma of the lung who had bacteremia involving Pseudomonas mesophilica. Of the common laboratory media tested at 35 degrees C, buffered charcoal yeast extract agar and nutrient agar provided the best growth; however, other media supported growth at lower temperatures. Since blood cultures are routinely subcultured onto chocolate agar and then incubated at 35 degrees C, awareness of the characteristics of P. mesophilica and of the isolation techniques as outlined may enhance the recovery of this and related bacterial species.